1. Field of the Invention
The present invention relates to a lithium polymer battery, and more particularly, to a lithium polymer battery that can improve reliability, safety and mechanical assembling workability of an electrical coupling structure between a bare cell and a protection circuit module.
2. Description of the Related Art
Generally, a lithium polymer battery includes, in one implementation, an electrode assembly, a pouch type outer case receiving the electrode assembly and a core pack formed of a protection circuit module that is provided at one side of the outer case so as to be electrically coupled to the electrode assembly.
The electrode assembly is formed by interposing a separator between first and second electrode plates and winding them together in a jelly-roll type. Electrode tabs are respectively attached to the first and second electrode plates and withdrawn out of the front of the outer case by a predetermined length.
The outer case, in one implementation, is a flexible pouch type and both sides and front thereof are thermally bonded. When the outer case is thermally bonded, remaining parts of a predetermined length are formed to protect the electrode assembly contained in the outer case. Accordingly, the remaining parts formed at both sides of the outer case are folded to surround the electrode assembly, thereby reducing a width of the battery. Then, the protection circuit module is placed on the remaining part formed on the front of the outer case.
However, in the conventional lithium polymer battery, a process of bending the electrode tabs is unavoidably performed while the protection circuit module is mechanically and electrically coupled to the electrode tabs withdrawn out of the front of the outer case.
For example, the electrode tabs may be bent to weld the connection terminal of the protection circuit module and electrode tabs at the same welding point. Or, when the connection terminal of the protection circuit module and electrode tabs are welded without bending the electrode tabs, the electrode tabs should be bent after welding. That is the reason that the process of bending the electrode tab should be performed to expose the external terminal of the protection circuit module.
As described above, the complicated process of bending the electrode tab has been unavoidably performed at least once while the outer case and protection circuit module are assembled.
Accordingly, the conventional lithium polymer battery has a problem that wire disconnection occurs at the bent part of the electrode tab and the reliability and safety of the battery are degraded.
In addition, assembling workability is lowered because of the complicated process to bend the electrode tab.